All You Need to Know About Functional Movement Screenings

As runners, we are all naturally keen to discover ways to avoid injury.

Despite this desire, the majority of us still manage to run into problems (pun intended) which suggests that we are all either really bad at listening to good advice, or the advice we are given was never that ‘good’ in the first place.

Research on how to stay injury free running is still a murky area. Studies into the causes of running injury often end up contradicting each other, and without knowing the cause it obviously makes it very tricky to offer advice.

In reality, no one can truly offer methods of injury prevention for runners but rather advice on how to reduce risk of injury.

This is an important distinction as it can help runners (and therapists) understand why a particular piece of advice may work for one runner but not for another.

Functional Movement Screening for Injuries

When it comes to reducing injury risk, one of the most current and popular methods being sold to therapists and runners is ‘movement screening.’

By watching the runner perform a series of specific movements, the therapist can spot ‘biomechanical flaws’ that unless corrected will increase risk of injury in the future.

One of the best known of these screens is the Functional Movement Screen (FMS) created by Gray Cook in 1997. The FMS is today used by coaches, trainers and rehab professionals all over the world to screen athletes of all shapes and sizes. By recognizing ‘mobility’ and ‘stability’ issues early, injury risk can in theory be predicted before it actually happens.

For each test, the athlete’s movement is rated 0 to 3. If pain occurs, a 0 is recorded.

Inability to perform the movement gets a 1, ability with ‘compensatory movement’ is given a 2, and ‘correct’ movement given a 3. The scores are totalled to give a final score out of 21, with scores under 14 signalling a greater risk of injury than those who with a score over 14.

Should We Call it a Screening or Assessment?

Screening is a medical procedure used to identify members of a population who despite displaying no symptoms are in fact carrying unrecognized disease or are at high risk of developing a specific disease.

Breast screening is a common example of this, and has proved to be an extremely important way of tackling breast cancer.

To call a series of movement tests a ‘screening’ assumes that the ‘flaws’ identified are indeed indicative of an as yet unrecognized ‘disease’, or in our case a way of moving that will increase the runner’s risk of injury.

And this is where the problem lies.

Research into the causes of running injury has yet to agree on any movements that predict injury or performance levels. Where one study links a particular movement with a particular running injury, another will show no correlation or occasionally the totally opposite.

The central premise of the FMS is that ‘compensatory movement patterns’ seen during the tests identify ‘weak links’ which unless corrected may increase injury risk and reduce performance.

The key word here is may, as recognized by the creators of FMS who in 2014 clarified that the FMS serves as “a directional role not a diagnostic role”.

So, the question is, how accurate are these movement screens?

What is the Accuracy of Movement Screens and is it Worth it?

When it comes to measuring the accuracy of a movement screen, there are a number of factors that need to be taken into account:

Test sensitivity: in a population of tested athletes, what percentage of the subjects who end up getting injured were correctly identified by the screening process?

Test specificity: in that same population of tested athletes, what percentage of the subjects who do not end up getting injured were correctly identified by the screening process?

Inter-rater reliability: How much do results differ for the same athlete but different testers? This is important as reliability of the screening will depend on who conducts it.

Inter-rater reliability: How much do results differ in repeated screenings on the same athlete by the same tester? This is particularly important as if the same tester is coming up with different results for the same athlete, the natural progression is to cast doubts on the reliability of the screening process itself.

Unfortunately, when it comes to movement screening, quality answers to the above questions are far and few between.

Most of the research to date has been conducted by the creators of movement screens themselves, which can obviously only therefore be taken at face value. Anecdotal evidence provided by therapists who have been on courses is likewise prone to suffering from confirmation bias.

The temptation to only remember the times when a particular test or treatment works and forget all the other times it doesn’t is a hard one to fight.

Let’s take a look at what we do know about movement and pain and see if that uncovers any limitations to movement screening.

Case Example: The Thomas Test

Although the Thomas Test is not a standard part of the typical movement screening, it does provide a good example of the limitations of a test.

The test involves having the runner sit on the edge of a bench, rolling back and then pulling both legs into the chest.

The runner then lets say the right leg extend downwards over the edge of the couch. If the back of this leg manages to make contact with the end of the couch, a result of ‘no restriction’ is recorded.

If instead the runner leaves a gap between the back of his leg and the couch, the result is ‘limited right hip extension.’ The angle of the knee is also used as an indicator of restriction, specifically in the rectus femoris (the quadriceps muscles that flexes the hip as well as extending the knee).

How does the Thomas Test score in terms of sensitivity and specificity?

Sadly, not very well.

One study (Schache et al, 2009) set out to compare degree of hip extension during running to degree of hip extension flexibility during the Thomas Test.

Their conclusion was as follows:

“Static hip extension ﬂexibility, measured using the Thomas test, was not found to be reﬂective of these dynamic movements (running)… It is advised that clinicians need to be extremely cautious about making predictions about the dynamic sagittal plane movements of the pelvis and hips based on the outcomes of the Thomas Test.”

Movement is context dependent

The problem with this test (and indeed any other that is not conducted during running) is that movement is context dependant.

Although we think of movement as being a product of tissue strength and flexibility, it is easy to forget the important role of the brain and nervous system.

When you move, the brain is continually comparing sensory input at that moment to a stored memory bank of every movement you have ever performed in your life.

The sensory input can be visual, vestibular, proprioceptive, and include visual horizon, orientation against gravity, joint compression, angle and torque, tissue tension and length. It is not hard to see that the sensory input the brain receives when lying on a couch is totally different to what it receives whilst running.

As a result, the movement seen in a test can be entirely different than that seen during actual running.

Along with this, the role of the brain in producing movement also signifies a departure from the traditional pursuance or ‘norms’ and ‘optimums’. Just as we see subtle differences in the running styles of the most successful runners in the world (and even variance amongst recreational runners), we must also accept that there is no one optimum way for any movement (unless your goal is to lift a very heavy weight, and even there they may be subtle differences).

This absence of optimums presents a big problem for movement screening as if we don’t know what should be happening, how can we label anything a ‘flaw,’ let alone start ‘correcting’?

How Do Different Body Types of Runners Affect Assessments?

As well as movement being context dependent, we also have to consider that sometimes people will always move differently during a test because of structural variance.

The squat, included in most movement screening, provides a good example of this.

Inability of a runner to reach a certain depth without coming up onto their toes, bending forwards excessively at the waist, rounding the back, bringing the arms forwards (in the case of an overhead squat test)… all of these are typically regarded as compensatory movements and predictors of injury.

Unfortunately, many testers are unaware that how a squat is performed can depend greatly on the runner’s natural anatomical makeup. Just like running form, there is not one optimum way to squat.

Let’s consider variance in thigh bone (femur) length relative to the length of the torso: a runner with a relatively longer thigh bone will always need to lean forwards more during a squat. Their physiological make up means they are not able to stay as upright or squat as deep as someone with a relatively shorter thigh bone.

In this case, trying to ‘correct’ their squat by improving ankle dorsiflexion mobility (commonly regarded as the ‘restrictor’ in a shallow squat) would be futile.

Devoting more time to other exercises such as leg presses, lunges and hip thrusters would probably be a good idea, but blaming injury or poor performance on their squat and trying to ‘correct’ it would not.

How solid is the evidence?

Like the squat, the single leg squat test also plays a regular part in most movement screens with the tester normally looking for excessive hip internal rotation and adduction (leg moving towards the midline).

Firstly, we need to recall that just as we saw with the Thomas Test, how a runner’s hip, knee and ankle move during a single leg squat test does not necessarily predict how they will move when running.

But in the case of this test, we also need to take a look at the conclusions normally taken from the test.

Research has indeed linked these (Meardon et al. 2012, 2014) but other research shows no association between hip adduction and ITB pain (Grau et al. 2008, 2011).

Likewise, although some research shows runners with patellofemoral pain syndrome (PFPS) exhibiting slightly more hip adduction during running and single leg squats, we must not forget all the runners who exhibit similar levels of hip adduction but are not suffering from PFPS.

To add to the confusion, when runners exhibiting ‘excess’ hip adduction given hip abduction strengthening exercises, some see their pain disappear but absolutely no change in their original ‘faulty’ levels of hip adduction.

These and other examples of contradictions within the research heavily suggest that we have to be careful not to rush into blaming injury and pain on ‘biomechanical flaws’ uncovered by movement screening.

Just because a prescribed ‘corrective exercise’ like glute medius strengthening sees a runner’s pain disappear after a period of time does not mean the ‘movement flaw’ identified was indeed a flaw. Many other factors could have been responsible for the pain subsiding: running less, eating better, sleeping more, not to mention the natural healing process finally kicking in.

This last point is an interesting one: when a runner decides to seek help from a professional, chances are the pain has already been going on for a fair while.

Whatever therapy you are given over the course of a month, there is always a chance that your body’s natural healing process played the major part in seeing the pain go, rather than the therapy or exercises you were given.

This is why it is so important for therapists to seek evidence based resolutions rather than the ‘latest fad’. How do you think the ‘rain dance’ came about in the first place?

Conclusion

Movement screening can be used to display a great deal of interesting information, but not enough to jump in and start diagnosing.

How someone performs say a single leg squat is a good measure of how they perform a single leg squat; we cannot unfortunately assume that that is how they will move when running. The creators of FMS acknowledge this in their literature but nevertheless there are many therapists out there who fall prey to the many red herrings thrown out by movement screening and the so called movement ‘flaws.’

Replacing the word ‘screening’ with ‘tests’ may help avoid such rabbit holes, because as at the end of the day these are ‘tests’, not diagnostic screening.

A common reaction from movement screening enthusiasts (particularly training providers) is that we are somehow suggesting that biomechanics is not important.

No one is saying this, it’s just we are not in a position to yet say when, where and how and for who. A true specialist in biomechanics will recognise that the more you look at the research, the more inconclusive it all becomes.

In the meantime, what has become clearer thanks to neuroscience research is that the brain and nervous system play a much larger role in pain than we once imagined, and whereas we once all interpreted pain as a product (and measure) of tissue damage and structural abnormality, we now need to see pain as a multifactorial experience.

Though the ‘corrections’ made after a movement screening may seem to lead to a decrease in injury or pain, it may not be for the reasons we perceive.

When it comes to reducing injury risk (and recovering from current injury), all of these factors can play just as important a role (and often more depending on the runner in question) as how you perform in a movement screen.

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